1. Field of the Invention
The invention relates to an encapsulated agent, preferably a biocidal preparation. In particular, the preparations of the invention provide a means for safely transporting a biocide such as an aldehyde, preferably glutaraldehyde, to an end-use destination and for preserving the biocidal activity of the biocidal agent until it is ready to be used at the destination.
2. Background Art
Aldehydes, and especially dialdehydes, can be potent biocidal compounds. One particular dialdehyde, glutaraldehyde, is a strong disinfectant. Glutaraldehyde is a 5-carbon molecule and possesses two aldehyde groups (i.e., a dialdehyde). Glutaraldehyde is the most potent disinfectant of the aldehyde class. It is available commercially as a 2 weight ("wt") % aqueous solution (Johnson & Johnson Co.) at pH 4.0. When made alkaline, pH 7.5-8.5, the 2 wt % glutaraldehyde is a rapid acting disinfectant. It is classified as a high-level germicide and is capable of producing sterility, i.e., eradicating all living bacteria, microorganisms and spores. Most bacteria are killed in less than 1 minute. Tubercie bacillus and viruses are killed in less than 10 minutes. And, bacterial spores are killed in less than 3 hours.
The 2 wt % glutaraldehyde solution has high stability when kept acidic. However, to be germicidal, the glutaraldehyde solution must be made alkaline. The alkaline glutaraldehyde solution is only stable for about 2 to 4 weeks. Under alkaline conditions, glutaraldehyde slowly polymerizes resulting in decreased germicidal activity.
The primary application for glutaraldehyde is as a cold disinfectant or sterilant or heat-sensitive medical and dental instruments. For disinfection, a 20 minute immersion in a 2 wt % glutaraldehyde alkaline solution is recommended. For sterilization, a 10-12 hour immersion is recommended. After immersion in the glutaraldehyde for the recommended time, the instruments are rinsed with sterile water.
Because of its strength as a disinfectant, care must be exercised when handling glutaraldehyde solutions, including the use of gloves and aprons when handling glutaraldehyde solutions. In addition, adequate ventilation should be provided when handling glutaraldehyde solutions. Glutaraldehyde solutions have been reported to produce contact dermatitis, eye irritation, nausea, headache, rashes, and asthmatic reactions.
U.S. Pat. No. 4,122,192 to Fellows discloses a glutaraldehyde containing disinfectant preparation. That preparation consists of glutaraldehyde (or a saturated dialdehyde of 2 to 6 carbons) absorbed and/or adsorbed on a carrier material. In some cases an alkalinating, activating agent is also included, which can be encapsulated in a water-soluble polymer. The '192 preparations suffer from several drawbacks. First, the glutaraldehyde itself is not isolated from human contact in the unused preparation. Second, the carrier material may freely enter the solution upon use of the preparation. Such entry into the cleaning solution of carrier material is undesirable. Furthermore, depending upon the original pH of the glutaraldehyde solution, some inactivation of the glutaraldehyde may occur in situ.
Because of its toxicity, glutaraldehyde is sold to the end-user as the 2 wt % glutaraldehyde aqueous solution. However, even the 2 wt % glutaraldehyde solution has toxicity and handling problems. A method of making aldehydes, particularly glutaraldehyde, safer to handle which lessens the toxicity and handling problems to the end-user is therefore highly desirable. Such a method would greatly increase the appeal of aldehydes, such as glutaraldehyde, as cold sterilants. In addition, there exists a need for a cost-effective mode of handling and delivering aldehydes. Finally, the method must provide a stable aldehyde or biocidal solution that can be readily and easily activated.